The correct answer is "thoroughly". Explanation & Key Takeaways: • In this sentence, we need an adverb that can describe the manner in which she studied. • "thoroughly" is an adverb that means "in a thorough or complete manner". • This suggests that the person studied comprehensively or meticulously, covering all necessary material. • This makes a logical sense in the context as t his manner of studying could lead to getting a high score in the exam. So, option 2 is the correct choice. Related Concepts: • The words "so," "rarely," and "slowly" are adverbs, and here is an explanation of their use along with examples: • "So" is often used as an intensifier to enhance the meaning of adjectives or adverbs. It can also be used to indicate the extent or degree of something. • Example: The movie was so interesting that I watched it twice. • Explanation: Here, "so" intensifies the adjective "interesting," indicating a high degree of interest. • "Rarely" is used to describe something that does not happen often; it's an adverb of frequency. • Example:She rarely eats out because she prefers cooking at home. • Explanation: "Rarely" indicates that eating out is an infrequent activity for her. • "Slowly" is used to describe the manner in which an action is done, indicating a slow speed or pace. • Example: He walked slowly down the hallway, lost in thought. • Explanation: "Slowly" describes how he walked, indicating that his pace was not fast.